Various types of antennas are rapidly improvement along with the development of the communication technology. The IC technology is also developed with fast pace to provide a product with smaller size and lighter weight. The volume fact is one of important considerations to the antenna used for transmitting and receiving signal. One goal of the manufacture is to achieve the small product with light weight.
Antenna is employed to transmit or receive EM wave. The characters of the antenna can be obtained from the operating frequency, radiation pattern, return loss and antenna Gain. Small size, good performance and low cost are the most important facts for the current antenna to share larger marketing.
Typically, the well-known 2.4 GHz omni-directional antenna mainly involves the so-called sleeve antenna structure or spring structure antenna. However, both of the systems are too huge, it is unlikely to achieve the size reduction purpose and can not adapted to the wireless USB adaptor that are configured in small space. On the other hand, the signal feeding end of the antenna needs additional control IC to adjust the impedance match. The design of the apparatus is complicated, thereby increasing the manufacture cost.
Thus, what is desired is to develop a cable type antenna to provide a product with smaller size, lighter weight, and with the omni-directional capability for achieving the reduction purpose. No additional impedance match circuit is needed.